The acquisition of three-dimensional (3D) surfaces is a problem which occurs frequently in mechanical and optical engineering, computer vision and many other application fields. Today's most precise methods involve active illumination by means of laser beams, lines or more sophisticated projection patterns. Usually, the light reflected or scattered by the surface is captured by an off-axis camera, so that the depth information can be recovered by triangulation. The usability of most of these methods is limited by the object material, which defines the reflectance properties. An ideal surface for this class of 3D scanners scatters an incoming ray of light diffusely into all directions so that each impinging light ray results in a well-defined hit point visible from any viewing direction. However, many objects and materials exhibit a reflectance that is highly uncooperative with regard to range scanning. Complex effects such as transparency, subsurface light transport, specular reflectivity, and interreflections between surface points pose a challenge for the design of a general and robust system for shape acquisition.